Site- and Regioselectivity of Nitrile Oxide–Allene Cycloadditions: DFT-Based Semiquantitative Predictions

Nitrile oxide 1,3-dipolar cycloaddition to arylsulfonyl- and dialkylaminoallenes have been investigated within the framework of the Kohn–Sham density functional theory (DFT) at the B3LYP/6-31G­(d,p) level. The hitherto-unexplained experimental behavior of sulfonylallenes was rationalized by transition-state calculations which enabled a semiquantitative treatment of the cycloaddition site- and regioselectivity. The reliability of DFT computations was further established by predicting the complete selectivity of the nitrile oxide cycloaddition to dialkylaminoallenes according to previous experimental findings.